Science 3-1 3-2
Energy Level
a region of an atom in which electrons of the same energy are likely to be found
Mass Number
the sum of neutrons and protons in an atomic nucleus
Periodic Table
An arrangement of the elements showing the repeating pattern of their properties
Isotope
An atom with the same number of protons and a different number of neutrons from other atoms of the same element.
Group
Elements in the same vertical column of the periodic table; also called family
Proton
Small, positively charged particles that are found in the nucleus of an atom
Atomic Mass
The average mass of all the isotopes of an element
Atom
The basic particle from which all elements are made; the smallest particle of an element that has the properties of that element
Atomic Number
The number of protons in the nucleus of an atom
Electron
A tiny, negatively charged particle that moves around the nucleus of an atom
Nucleus
1. In cells, a large oval organelle that contains the cell's genetic material in the form of DNA and controls many of the cell's activities. 2. The central core of an atom which contains protons and neutrons. 3. The solid core of a comet.
Period
A horizontal row of elements in the periodic table
Chemical Symbol
A one or two letter representation of an element
Neutron
A small particle in the nucleus of the atom, with no electrical charge